Power optimization for frequent service loss

Abstract

Apparatus and methods related to acquiring service on mobile computing devices (MCDs) are provided. A method includes determining a decreasing sequence of scan ratios, each scan ratio indicating a proportion of time over which a MCD scans one or more frequencies to attempt connection with a wireless network during a disconnected time window. The method further includes determining a connected time window′ when the MCD is connected to the wireless network. The method additionally includes determining a ping-pong rate for the MCD based at least on a duration of the connected time window. The method also includes selecting a scan ratio from the decreasing sequence of scan ratios based on the ping-pong rate. The method further includes scanning the one or more frequencies in accordance with the decreasing sequence of scan ratios and starting from the selected scan ratio to cause the MCD to attempt connection with the wireless network.

The invention claimed is: 
     
       1. A computer-implemented method, comprising:
 determining a decreasing sequence of scan ratios, each scan ratio indicating a proportion of time over which a mobile computing device scans one or more frequencies to attempt connection with a wireless network during a disconnected time window when the mobile computing device is disconnected from the wireless network; 
 determining a connected time window when the mobile computing device is connected to the wireless network, the connected time window occurring after the disconnected time window; 
 determining a ping-pong rate for the mobile computing device based at least on a duration of the connected time window; 
 selecting a scan ratio from the decreasing sequence of scan ratios based on the ping-pong rate; and 
 scanning the one or more frequencies in accordance with the decreasing sequence of scan ratios and starting from the selected scan ratio to cause the mobile computing device to attempt connection with the wireless network. 
 
     
     
       2. The method of  claim 1 , wherein when the duration is less than a first threshold, the ping-pong rate is determined to be a high ping-pong rate and the selected scan ratio is a most recently used scan ratio from the decreasing sequence of scan ratios. 
     
     
       3. The method of  claim 2 , wherein when the duration is greater than the first threshold and less than a second threshold, the ping-pong rate is determined to be a medium ping-pong rate and the selected scan ratio is a midpoint scan ratio between the most recently used scan ratio and an initial scan ratio from the decreasing sequence of scan ratios. 
     
     
       4. The method of  claim 3 , wherein when the duration is greater than the second threshold, the ping-pong rate is determined to be a low ping-pong rate and the selected scan ratio is the initial scan ratio from the decreasing sequence of scan ratios. 
     
     
       5. The method of  claim 1 , wherein each scan ratio is associated with a sleep duration, and wherein scanning the one or more frequencies starting from the selected scan ratio comprises waiting the associated sleep duration in between consecutive scanning periods. 
     
     
       6. The method of  claim 1 , wherein the one or more frequencies comprise a plurality of frequencies, wherein scanning the one or more frequencies comprises scanning each frequency of the plurality of frequencies in sequence. 
     
     
       7. The method of  claim 1 , wherein the decreasing sequence of scan ratios corresponds to a sequence of stages, wherein scanning the one or more frequencies in accordance with the decreasing sequence of scan ratios and starting from the selected scan ratio comprises resetting a stage timer that progresses through the sequence of stages. 
     
     
       8. The method of  claim 1 , wherein determining the decreasing sequence of scan ratios is based on a scanning context. 
     
     
       9. The method of  claim 8 , wherein selecting the scan ratio is further based on the scanning context. 
     
     
       10. The method of  claim 8 , wherein the scanning context comprises at least one of a mobility attribute, a location attribute, a thermal attribute, or a screen attribute. 
     
     
       11. The method of  claim 1 , wherein the ping-pong rate is further based on at least one duration of at least one previous connected time window. 
     
     
       12. The method of  claim 11 , where the ping-pong rate is based on a weighted average of the duration of the connected time window and the at least one duration of the at least one previous connected time window, wherein weights for the weighted average are greater for more recent time windows. 
     
     
       13. The method of  claim 1 , wherein the decreasing sequence of scan ratios is a first sequence, the method further comprising:
 determining a second decreasing sequence of scan ratios, each scan ratio indicating a proportion of time over which the mobile computing device scans one or more different frequencies to attempt connection with the wireless network during the disconnected time window; 
 selecting a second scan ratio from the second sequence of scan ratios based on the ping-pong rate; and 
 scanning one or more different frequencies in accordance with the second sequence of scan ratios and starting from the second selected scan ratio to cause the mobile computing device to attempt connection with the wireless network. 
 
     
     
       14. The method of  claim 13 , wherein the one or more frequencies are selected from a set containing recently acquired frequencies, wherein the one or more different frequencies are selected from a set containing a full band of frequencies. 
     
     
       15. The method of  claim 14 , further comprising determining a mobility attribute of the mobile computing device, wherein the decreasing sequence of scan ratios and the second decreasing sequence of scan ratios are based on the mobility attribute. 
     
     
       16. The method of  claim 15 , wherein when the mobility attribute indicates high mobility and the ping-pong rate is determined to be a medium ping-pong rate, the selected scan ratio is a first midpoint scan ratio between a most recently used scan ratio and an initial scan ratio from the decreasing sequence of scan ratios and the second selected scan ratio is a second midpoint scan ratio between a most recently used scan ratio and an initial scan ratio from the second decreasing sequence of scan ratios. 
     
     
       17. A mobile computing device, comprising:
 one or more processors; and 
 one or more computer readable media having computer-readable instructions stored thereon that, when executed by the one or more processors, cause the mobile computing device to carry out functions comprising: 
 determining a decreasing sequence of scan ratios, each scan ratio indicating a proportion of time over which the mobile computing device scans one or more frequencies to attempt connection with a wireless network during a disconnected time window when the mobile computing device is disconnected from the wireless network; 
 determining a connected time window when the mobile computing device is connected to the wireless network, the connected time window occurring after the disconnected time window; 
 determining a ping-pong rate for the mobile computing device based at least on a duration of the connected time window; 
 selecting a scan ratio from the decreasing sequence of scan ratios based on the ping-pong rate; and 
 scanning the one or more frequencies in accordance with the decreasing sequence of scan ratios and starting from the selected scan ratio to cause the mobile computing device to attempt connection with the wireless network. 
 
     
     
       18. An article of manufacture comprising one or more non-transitory computer readable media having computer-readable instructions stored thereon that, when executed by one or more processors of a mobile computing device, cause the mobile computing device to carry out functions that comprise:
 determining a decreasing sequence of scan ratios, each scan ratio indicating a proportion of time over which the mobile computing device scans one or more frequencies to attempt connection with a wireless network during a disconnected time window when the mobile computing device is disconnected from the wireless network; 
 determining a connected time window when the mobile computing device is connected to the wireless network, the connected time window occurring after the disconnected time window; 
 determining a ping-pong rate for the mobile computing device based at least on a duration of the connected time window; 
 selecting a scan ratio from the decreasing sequence of scan ratios based on the ping-pong rate; and 
 scanning the one or more frequencies in accordance with the decreasing sequence of scan ratios and starting from the selected scan ratio to cause the mobile computing device to attempt connection with the wireless network.